Phase Behavior of the System Linear Polyglycerol + Methanol + Carbon Dioxide

Abstract

To compare the phase behavior of linear and hyperbranched polymers, the phase envelopes of the ternary system linear polyglycerol þ methanol þ carbon dioxide were determined for polymers of varying molar mass. Phase changes were detected by a static synthetic method using the Cailletet setup for temperatures between 331 K and 421 K and pressures up to 13.1 MPa. Besides the vaporÀliquid and liquidÀliquid equilibria, also the vaporÀliquid to vaporÀliquidÀliquid and vaporÀliquidÀliquid to liquidÀliquid phase boundaries are reported. The experimental results are similar to systems with hyperbranched polymers (rather than linear polymers). For the systems with linear polymers, however, the bubble-point pressures show no significant dependence on the polymer molar mass, whereas for hyperbranched polymers the bubble-point pressure was found to vary substantially with the polymer molecular mass. Further, the polymer concentration at the lower critical solution temperature is remarkably high when the polymers have a hyperbranched structure (Schacht et al., Fluid Phase Equilib. 2010, 299, 252À258), while the polymer concentration is much lower for systems with linear polymers.

Beyond Poly(ethylene glycol): Linear Polyglycerol as a Multifunctional Polyether for Biomedical and Pharmaceutical Applications

“…To date, several low molecular weight initiators including potassium tert-butoxide (t-BuOK), 36,37,40,41 potassium 3-phenyl propanolate (PPOK), 39,41,42 alkoxy ethanolates, 43,44 potassium methoxide (MeOK) 43,45 or BuLi/phosphazene base (Li + /t-BuP 4 ) 41 have been successfully applied to polymerize EEGE in a controlled manner (Scheme 1). In an interesting work by Moller, Keul et al homo-and random copolymers of EEGE, tBGE and AGE have been prepared by anionic ring-opening polymerization, and the authors studied selective removal of the protecting groups.…”

“…To date, several low molecular weight initiators including potassium tert -butoxide ( t -BuOK), ,,, potassium 3-phenyl propanolate (PPOK), ,, alkoxy ethanolates, , potassium methoxide (MeOK) , or BuLi/phosphazene base (Li + / t -BuP 4 ) have been successfully applied to polymerize EEGE in a controlled manner (Scheme ).…”

Hyperbranched Polymers in a Supercritical Fluid: Recent Progress on Phase Behavior and Modeling

“…Besides the low-pressure studies mentioned above, Seiler, et al [57] [62,63]. The bubble-point pressures for the linear polymer system did not change much with the increase in the molecular weight of the polymer, while for hyperbranched polymer system the molecular weight showed a more pronounced effect on the bubble-point pressures, indicating that the branched structure is the main reason for the dependence of bubble-point pressures on the polymer size.…”

“…However, the difference in phase behavior of hyperbranched polymers and its linear analogue is still not very clear. Schacht, et al [62,63] made a comparison of the phase behavior of hyperbranched polyglycerol + methanol + CO 2 and the ternary system of linear polyglycerol in the same solvents. Although they found some interesting observations on the difference in molecular weight dependence, the phase behavior data of hyperbranched polymer and linear polymer system cannot be directly compared on the same condition because molecular weight effect cannot be eliminated.…”

High-Pressure Phase Behavior for Poly(ethylene glycol) and 1,1,1,2-Tetrafluorethane Systems

“…The majority of the investigations on high-pressure polymeric nanoparticles, reported in the literature, deals with a carbon dioxide precipitating agent. , The phase behavior of the chosen polymer and pharmaceutical drug in the high-pressure solvent plays a crucial role in the design of an efficient controlled -release system. , Because of the very low solubility of the majority of polymers in carbon dioxide, experimental data of phase equilibria of polymeric system in this gas were measured with organic solvents as entrainers. − …”